Minimum AC3 bitrate for 5.1 channel

[iKron]

what is the minimum suitable bitrate for AC3 audio? is 256kbps is good enough? i want to convert some bluray movie DTS audio to AC3 without losing much data.

[joearmstrong]

Minimum bitrate for AC3 5.1 is 384kbps, recommended is 448kbps or better, up to 640kbps.
DVDs have 384kbps and 448kbps for AC3 5.1 - 256kbps is only suited for Stereo.

For best quality you should convert to 640kpbs.

[Skiller]

256 Kbit/s is way too low for 5.1 AC3 to sound acceptable.
I agree 384 KBit/s is about the minimum you may use, but better go higher if you can.
Note that for DVD 448 is the maximum allowed; 640 is not DVD compliant (although it should work fine in almost all cases anyway).

[pandy]

what is the minimum suitable bitrate for AC3 audio? is 256kbps is good enough? i want to convert some bluray movie DTS audio to AC3 without losing much data.

Transcoding from DTS to AC-3 may be sub-optimal (never found deeptrough analysis how DTS artifacts will affect DCT based codecs) - in your case i would do some tests and will try to find some sweet spot between bitrate and quality - it should be quite fast - ffmpeg and simple script should be fine.
Afraid that there is no free (open source) AC-3 codec capable to provide quality (VBR) focused encoding - you may try to reduce bandwidth (low pass) in FC + surround channels - this may help in bitrate allocation for both Front channels so perhaps 256...320kbps will be quality acceptable.

[iKron]

thank you all, i think i will use 448.

[tuskacz]

Anything above 320kbps.
Below this = MP3 quality not AC3.

[bar72]

Searched google for the same question and was brought here! Bumped for future refrence

[pandy]

Searched google for the same question and was brought here! Bumped for future refrence

You can add also this thread https://forum.videohelp.com/threads/409055-Minimum-AC3-Bitrate-for-5-1-Stereo

Dolby Labs declaring 64Kbps as usually enough for channel.